Fueling Performance CHO Intake and Timing

Fuel

short term, getting energy for exercise, energy nutrient- CHO and fat

metabolic symptoms that use food for energy to support life and training and exercise, food has energy, has calories within it, energy=calories

You want to maintain muscle glycogen (stored carbohydrate), CHO is stored as glycogen in the muscle and liver, maintenance of glycogen stores is crucial to training and performance, CHO is stored mostly in the muscle and less in the liver as glycogen

skeletal muscle glycogen: 300-400 g

liver glycogen: ~80-100g

bioenergetics

creatine phosphate/phosphogen system: creatine, red meat and supplementation

glycolysis: carbohydrate (glycogen, glucose)

oxidative phosphorylation (aerobic system): carbohydrate fat

CHO need

depends on who is your population, who is your client, what are their training demands (volume, intensity, frequency, duration), are modifications necessary?

athlete: have higher training demands and therefore have higher CHO demand

CHO is a versatile fuel, it’s used in long-term system (aerobic) and short-term system (glycolysis), can generate ATP through anaerobic and aerobic pathways

long-term system (aerobic): longer-duration intense endurance exercise

short-term system (glycolysis): shorter-duration intense anaerobic exercise

CHO and performance

aerobic/endurance activities (>60-90 mins of 65-80% VO2max), moderate-high intensity

repeated/high volume short-duration high intensity activities

the higher the intensity, the higher CHO intake needed

CHO and Training: glycogen progressively decreases with repeated intense training/performance, must be maintained/replenished (daily intake, loading, during performance, recovery), you want to avoid this depletion because it will result in lower performance

Resistance exercise and glycogen use: not super glycogen demanding, an acute bout can reduce muscle glycogen concentrations by ~25% - 40% unless repeated intense resistance exercise of same muscle, risk of depletion is low, if you’re doing non-athletic RT you’re probably not gonna run out of muscle glycogen so there’s not a high demand of CHO needed, endurance training has higher demand

CHO intake

general fitness program training: 45-55% kcal/d, 2000 kcals/d = 225-275 grams per day

moderate volumes of training: 5-6 days/week at 2-3 hrs/day, 5-8 g/kg/d, 55Kg person = 275-440 grams per day, 77 kg person = 385 - 616 grams per day

high volume intense training: 5-6 days/week at 3-6 hrs/day; 1-2 workouts per day, 8-10g/kg/d, 55 kg person = 440 - 550 grams per day, 77 kg person = 616 - 770 grams per day

most non athletes do not need high CHO intake

unless an athlete, a single bout of exercise will not deplete glycogen, consecutive days of exhaustive exercise (same muscles) can lead to glycogen depletion, athletes

average training load (intensity, volume, frequency) of training will not deplete/significantly reduce glycogen, training frequency allows for replenishment, most training not consecutive days of exhaustive exercise (of same muscle group)

depletion rare and ample time for replenishment in non-athletes, modest, even low-CHO diet likely suitable for most non-athletes

however, as training load increases, so should CHO intake

current CHO recommendations for RT

not as well established as endurance exercise,

moderate daily intake, 3-5 g/kg/d, strength/power athletes

4-5 g/kg/d, bodybuilders

RT reduces muscle glycogen 30-40%

Pre-exercise CHO: no effect on RT performance

high glycogen vs low glycogen: less than strong evidence for performance benefit (if you train with lower glycogen you’re probably still going to be ok

low CHO diet, no effect on RT performance, no effect on strength outcomes (you can engage in low CHO diet and still train well

hypertrophy occurs with low/no CHO intake (keto), gains/maintenance greater in non-low CHO diet, may be through water losses, hypertrophy can still happen with low CHO diet

lower, moderate, high CHO intake likely adequate, training frequency allows for replenishment, RT programs 2-3 days between training muscle groups, depletion rare and ample time for replenishment (even low-modest CHO intake), LBM differences possible from decreases in TBW, CHO intake for RT isn’t as important as CHO intake for endurance, unless you are doing the same muscle within 24 hours or consecutive days, the idea of completely restoring muscle glycogen levels to pre-exercise levels is not really a big concern

fat

no hard fat recommendations for exercise/performance (both aerobic and RT), general guidelines apply, slightly greater, ISSN, 30% kcals/d, up to 50% during high volume training, abstain from very low fat diets < 10-20% kcals, maintenance of intramuscular triglycerides, essential fatty acids

low-CHO ketogenic diets and endurance training

proposed to enhance aerobic performance and adaptation, 70-80% kcals/d (high in fat diet), fat loading, fat adaptatio, metabolic enhancements (increased ability to oxidize fat, glycogen sparing, increasing lactate threshold, body better at using fat as fuel, and the idea is that it is going to boost performance because ability to burn fat is higher BUT THAT IS NOT THE CASE

keto diet, better for people during very long duration at low intensity since they are using fat, it impairs performance that would benefit from CHO, higher intensity performance, longer duration performance, more fat burning does not increase performance, but rather impairs it

recreational athletes: able to maintain performance while running at 40-60% VO2max

well-trained athletes: able to maintain performance while running at 70% VO2max

elite runners: performance suffered on all fronts running at 85-95% VO2max and had minimal fat oxidation

nutrient timing

purposeful ingestion of all types of nutrients at various times throughout the day to favorably impact the adaptive response to acute and chronic exercise (i.e., muscle strength and power, body composition, substrate utilization, and physical performance, etc.).

CHO timing

daily meals: reaching CHO intake and maintenance of daily glycogen levels

pre-workout meals: maintenance of blood glucose

intra-workout meals: maintenance of blood glucose and glycogen sparing

post-workout meals: restoration of glycogen

synthesis of muscle glycogen from CHO intake takes 4 hours, increasing small frequency and strategic timing crucial

Atletes CHO intake: 5-12 g/kg/d, 8010g/kg/d athletes training at moderate to high intensities, (> 70% VO2max) upwards of 12 h per week, glycogen stores maximized at 8-12 g/kg/d

strength and power athlets may requires less, lower CHO intakes appear not to hinder RT performance and strength outcomes, maybe hypertrophy, females may need to increase calorie intake to acheive simialr glycogen loading

maintenanc, leading up to competition: several days of high CHO intake (8-12 g/kg/d) maximizes glycogen stores, one day of 10g/kg high glycemic CHO, rapid storage (1-2g/kg/h)

pre exercise: 1-4 g/kg CHO several hours pre training/competition to increase glycogen stores, CHO intake 30-60 min pre-exercise to maintiain blood glucose and glycogen sparing (liquid may be preferred GI distress), addition of protein to CHO can improve endurance performance

intr-workout: maintenance of bloof glucose, glycogen sparing, 12-16 oz of 6-8% CHO >70 min endurance exercises, CHO intake during high volume RT (small snacks, bars, gels, drinks, etc)

post exercise: >1.2 g/kg/h for 4-6 h post exhaustive exercise, adding 0.2-0.5 g/kg/h protein with <1.2 g/kg/h CHO, glycogen restoration enhanced immedate to 6h post, addition of ceffeine 3-8 mg/kg increases glycogen restoration

glycogen repletion

post-exerciseL consume higher glycemic CHO since they get broken down faster and so it gets into bloodstream faster, which allows the muscle to store new glycogen faster

CHO considerations

CHO needed=glycogen needed, volume and intesnity, frequnecy, duration, time between training/competition

frequent and high training loads require greater daily CHO, longer duration actigivty with greater CHO and CHO during, training/performance with minimal/little time between bouts requore agressive CHO intake post-exercise, non-athletes likely do not require aggressive CHO strategies

summary

athletes: focus on maximizing glycogen (5-10kg/d, pre, intra, post CHO, training and competition)

non-athletes: some to a lot of CHO find, adjust according to training

it’s not jsut intensity it’s also duration